Catalytic cracking



July 28, 1942. R E, BURK 2,291,292

CATALYTIC CRACKING Filed May 15, 1939 GASOLI NE/\ Ol! VAPORIZABLE ggg-ED g'E-I NG CAT/UST l LIQUID RESIDUUM AND Y CONDENSED CATA YST\ :/^\|'/\LYSTw FILTER LIQUID RESIDUUM Invent-(w:

Robert E. BLWK @Xml-W www@ BH Jtty Patented July 28, 1942 UNTED 2,291,292 ca'rnmzfrro caacnnvo Application May 15, 1939, Serial No. 273,677

(Cl. 19E-52) 6 Claims.

In cracking petroleum stocks with a catalyst, coke becomes mixed with the catalyst and must be burned off and this is a tedious and critical operation which is also prone to more or less damage the catalyst. With heavy or residual stocks the coke production is so large as to render this form or" cracking impracticable. In accordance with the present invention, however, catalytic conversion of hydrocarbons to lower boiling products or cracking may be carried out with elimination of necessity of burning coke off the catalyst, and it becomes possible to operate with stocks which are also of the heavier or residual type.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indictative however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing, the sole figure is a diagrammatic illustration on the order of a ow sheet showing one manner of practicing the invention.

Any usual or desired cracking stock, as gas oils or lighter materials, or heavier residual stocks may be employed in accordance with the invention. It is particularly advantageous in that residual stocks which otherwise make too much coke trouble, can be satisfactorily treated. The hydrocarbons to be cracked are subjected to the action of the catalyst at elevated temperature, e. g. 650-1250 F., and preferably at temperatures of 7501050 E'. Pressure may rang@ from about one atmosphere to for instance 800 pounds per square inch. The rate of supply of the cracking stock relative to the catalyst may vary, depending upon the particular materials and temperature, and may be 0.1 to 1000 vol. per vol. of catalyst per hour, volume being reckoned in the vapor phase. With particular advantage, continuous type operation may be carried on, the cracking stock and the catalyst being fed to the hot zone. In some instances it is advantageous to include available water, as steam or water with the feed. The catalysts which I employ in accordance with the invention are in general of acidic nature and are liquids or vapors under reaction conditions and have the peculiarity of being separable after the operation by cooling and condensing, being filtered off if in solid state or separated by phase-separation if in the liquid 55 state, or the catalyst may be leached out. Examples of such catalyst are arsenic oxides.

As an illustrative example: A 50 per cent reduced Illinois crude petroleum used as stock was fed at the rate of 4 parts of oil by weight to 1 part of AszOs, the temperature of the cracking Zone being maintained at about 930 F. or slightly more, water being supplied with the feed at the.

rate of 1 'volume per 220 volumes of stock. The reaction rate constant K was about .66 (measured in minutes) as against .18 where the AszOs was omitted, and with a 20.1 per cent volume yield of gasoline on the feed the product showed a Kattwinkel test of '74 and a knock rating of 98.5, as against a Kattwinkel test of 62 and knock rating of 92.5 where the catalyst was omitted. (Knock rating is the customary standard used by the industry, expressed in octane numbers as determined by mixtures of the fuel and lead tetraethyl compared with iso-octane in a standard knock-testing engine.) The arsenic oxide is iinally filtered off from the heavy material, and is desirably re-cycled back into the feed.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a process of converting hydrocarbons to lower boiling products, passing a residual petroleum stock through a hot zone at a temperature of about 930 F. in admixture with arsenious oxide 1 part by weight to 4 parts of oil, the arsenious oxide being thereby vaporized, and subsequently cooling and condensing and filter-separating the arsenious oxide and returning it to the hot Zone.

2. In a process of converting hydrocarbons to lower boiling products, passing the hydrocarbons to be converted together with water molecules through a hot zone in admixture with arsenious oxide, the arsenious oxide being thereby vaporized and subsequently cooling and condensing and filter-separating the arsenious oxide and returning it to the hot zone.

3. In a process of converting hydrocarbons to lower boiling products, passing the hydrocarbons to be converted through a hot zone in admixture with arsenious oxide, the arsenious oxide being thereby vaporized and subsequently cooling and condensing and filter-separating the arsenious oxide and returning it to the hot zone.

4. In a process of converting hydrocarbons to lower boiling products, subjecting a residual petroleum stock to contact with vaporized arsenious oxide at a temperature of about 930 F., and withdrawing the arsenious oxide with the hydrocarbons from the high temperature zone and subsequently separating the arsenious oxide by change in physical state.

5. In a process of converting hydrocarbons to lower boiling products, subjecting the hydrocarbons to be converted together with water molecules to contact with vaporized arsenious oxide at elevated temperature, and withdrawing the arsenious oxide with the hydrocarbons from the high temperature zone and subsequently separating the arsenious oxide by change in physical state and returning it to the hot Zone.

6. In a process of converting hydrocarbons to lower boiling products, subjecting the hydrocarbons to be converted to contact with Vaporized arsenious oxide at elevated temperature, and withdrawing the arsenious oxide with the hydrocarbons from the high temperature zone and subsequently separating the arsenious oxide by change in physical state and returning it to the hot zone.

ROBERT E. BURK. 

